I'm trying to use instancing to show a star field with a billboard. The stars have varying colors, so that will have to be in there as well as position and scale. I have the position part working, but if I try to add anything else to the layout, it fails. Here is a snippet of the relevant code:

	D3D11_INPUT_ELEMENT_DESC polygonLayout[4];

	polygonLayout[0].SemanticName = "POSITION";
	polygonLayout[0].SemanticIndex = 0;
	polygonLayout[0].Format = DXGI_FORMAT_R32G32B32_FLOAT;
	polygonLayout[0].InputSlot = 0;
	polygonLayout[0].AlignedByteOffset = 0;
	polygonLayout[0].InputSlotClass = D3D11_INPUT_PER_VERTEX_DATA;
	polygonLayout[0].InstanceDataStepRate = 0;

	polygonLayout[1].SemanticName = "TEXCOORD";
	polygonLayout[1].SemanticIndex = 0;
	polygonLayout[1].Format = DXGI_FORMAT_R32G32_FLOAT;
	polygonLayout[1].InputSlot = 0;
	polygonLayout[1].AlignedByteOffset = D3D11_APPEND_ALIGNED_ELEMENT;
	polygonLayout[1].InputSlotClass = D3D11_INPUT_PER_VERTEX_DATA;
	polygonLayout[1].InstanceDataStepRate = 0;


	polygonLayout[2].SemanticName = "TEXCOORD";
	polygonLayout[2].SemanticIndex = 1;
	polygonLayout[2].Format = DXGI_FORMAT_R32G32B32_FLOAT;
	polygonLayout[2].InputSlot = 1;
	polygonLayout[2].AlignedByteOffset = 0;
	polygonLayout[2].InputSlotClass = D3D11_INPUT_PER_INSTANCE_DATA;
	polygonLayout[2].InstanceDataStepRate = 1;

	polygonLayout[3].SemanticName = "TEXCOORD";
	polygonLayout[3].SemanticIndex = 1;
	polygonLayout[3].Format = DXGI_FORMAT_R32G32B32_FLOAT;
	polygonLayout[3].InputSlot = 1;
	polygonLayout[3].AlignedByteOffset = D3D11_APPEND_ALIGNED_ELEMENT;
	polygonLayout[3].InputSlotClass = D3D11_INPUT_PER_INSTANCE_DATA;
	polygonLayout[3].InstanceDataStepRate = 1;

	// Get a count of the elements in the layout.
	numElements = sizeof(polygonLayout) / sizeof(polygonLayout[0]);

	// Create the vertex input layout.
	result = GE->Graphics.dev->CreateInputLayout(polygonLayout, numElements, vertexShaderBuffer->GetBufferPointer(), vertexShaderBuffer->GetBufferSize(), 
					   &m_layout);
	if(FAILED(result))
	{
		if (result==E_INVALIDARG) tp1=1;
		if (result==E_OUTOFMEMORY) tp1=2;
		if (result==E_NOTIMPL) tp1=3;
		if (result==S_FALSE) tp1=4;
		return false;
	}

And the vertex shader:

/////////////
// GLOBALS //
/////////////
cbuffer MatrixBuffer
{
    matrix worldMatrix;
    matrix viewMatrix;
    matrix projectionMatrix;
};


//////////////
// TYPEDEFS //
//////////////


struct VertexInputType
{
    float4 position : POSITION;
    float2 tex : TEXCOORD0;
    float3 instancePosition : TEXCOORD1;
	float3 instancedColor : TEXCOORD2;
};

struct PixelInputType
{
    float4 position : SV_POSITION;
    float2 tex : TEXCOORD0;
//	float4 color : COLOR;
};


////////////////////////////////////////////////////////////////////////////////
// Vertex Shader
////////////////////////////////////////////////////////////////////////////////
PixelInputType PointSpriteVertexShader(VertexInputType input)
{
    PixelInputType output;
    

    // Change the position vector to be 4 units for proper matrix calculations.
    input.position.w = 1.0f;


    // Update the position of the vertices based on the data for this particular instance.
    input.position.x += input.instancePosition.x;
    input.position.y += input.instancePosition.y;
    input.position.z += input.instancePosition.z;

    // Calculate the position of the vertex against the world, view, and projection matrices.
    output.position = mul(input.position, worldMatrix);
    output.position = mul(output.position, viewMatrix);
    output.position = mul(output.position, projectionMatrix);
    
    // Store the texture coordinates for the pixel shader.
    output.tex = input.tex;
//	output.color.xyz=input.instancedColor;
//	output.color.w=1;

    return output;
}

If I remove the color information from the description and the vertex shader, it runs fine. When I have the color info in, it fails and says it's E_INVALIDARG. I've tried to find an example of instancing that uses position and color, but nothing.....

As it happens (and it happens more than I would like), I posted something JUST BEFORE the solution presented itself.

The SemanticIndex for the second instanced description should have been set to 2.......